Multiple-tip edge couplers with segmented waveguide cores

Abstract

Structures for an edge coupler and methods of fabricating a structure for an edge coupler. The structure comprises an edge coupler including a first waveguide core and a second waveguide core adjacent to the first waveguide core in a lateral direction. The first waveguide core includes a first section with a first thickness and a first plurality of segments projecting in a vertical direction from the first section. The second waveguide core includes a second section with a second thickness and a second plurality of segments projecting in the vertical direction from the second section.

What is claimed is: 
     
       1. A structure comprising:
 an edge coupler including a first waveguide core and a second waveguide core adjacent to the first waveguide core in a lateral direction, the first waveguide core including a first section with a first thickness and a first plurality of segments projecting in a vertical direction from the first section, and the second waveguide core including a second section with a second thickness and a second plurality of segments projecting in the vertical direction from the second section, 
 wherein the first waveguide core includes a third section with a third thickness, and the first plurality of segments have a first height relative to the first section of the first waveguide core equal to a difference between the first thickness and the third thickness. 
 
     
     
       2. The structure of  claim 1  wherein the edge coupler further includes a third waveguide core adjacent to the first waveguide core in the lateral direction, the third waveguide core including a fourth section with a fourth thickness and a third plurality of segments projecting in the vertical direction from the fourth section. 
     
     
       3. The structure of  claim 2  wherein the first waveguide core is positioned in the lateral direction between the second waveguide core and the third waveguide core. 
     
     
       4. The structure of  claim 2  wherein the fourth thickness is equal to the second thickness. 
     
     
       5. The structure of  claim 1  wherein the first thickness is equal to the second thickness. 
     
     
       6. The structure of  claim 1  wherein the second plurality of segments have a second height relative to the second section of the second waveguide core equal to a difference between the third thickness and the second thickness. 
     
     
       7. The structure of  claim 1  further comprising:
 a light source positioned adjacent to the first waveguide core and the second waveguide core, the light source configured to provide light in a mode propagation direction to the first waveguide core and the second waveguide core. 
 
     
     
       8. The structure of  claim 7  wherein the first waveguide core is terminated by the one of the first plurality of segments, and the second waveguide core is terminated by the one of the second plurality of segments. 
     
     
       9. The structure of  claim 7  wherein the light source is a semiconductor laser. 
     
     
       10. The structure of  claim 7  wherein the light source is an optical fiber. 
     
     
       11. The structure of  claim 7  wherein the first waveguide core has a width that increases with increasing distance from the light source. 
     
     
       12. The structure of  claim 7  wherein the second waveguide core has a width that decreases with increasing distance from the light source. 
     
     
       13. The structure of  claim 7  wherein the second waveguide core has a width that is constant with increasing distance from the light source. 
     
     
       14. The structure of  claim 7  further comprising:
 a substrate, 
 wherein the substrate includes a cavity having an undercut that extends beneath at least a portion of the first waveguide core and the second waveguide core, and the light source is positioned in the cavity. 
 
     
     
       15. The structure of  claim 1  wherein the first waveguide core further includes a rib overlaid with the first section and at least some of the first plurality of segments. 
     
     
       16. The structure of  claim 1  wherein the first plurality of segments are separated by a first plurality of gaps, the second plurality of segments are separated by a second plurality of gaps, a dielectric material is positioned in the first plurality of gaps and the second plurality of gaps, the first plurality of segments and the second plurality of segments comprise a first material having a first dielectric constant, and the dielectric material comprises a second material having a second dielectric constant that is less than the first dielectric constant. 
     
     
       17. The structure of  claim 16  wherein the first plurality of segments and the dielectric material define a first metamaterial structure, and the second plurality of segments and the dielectric material define a second metamaterial structure. 
     
     
       18. The structure of  claim 1  wherein the second waveguide core has a tapered width. 
     
     
       19. A method comprising:
 forming an edge coupler including a first waveguide core and a second waveguide core adjacent to the first waveguide core in a lateral direction, 
 wherein the first waveguide core includes a first section with a first thickness and a first plurality of segments projecting in a vertical direction from the first section, the second waveguide core includes a second section with a second thickness and a second plurality of segments projecting in the vertical direction from the second section, the first waveguide core includes a third section with a third thickness, and the first plurality of segments have a first height relative to the first section of the first waveguide core equal to a difference between the first thickness and the third thickness. 
 
     
     
       20. The method of  claim 19  further comprising:
 forming a cavity adjacent to the edge coupler, 
 wherein the cavity is configured to receive a light source that is positioned adjacent to the first waveguide core and the second waveguide core, and the light source is configured to provide light in a mode propagation direction to the first waveguide core and the second waveguide core.